Do the following configuration steps on each of the nodes in the cluster.
If your instance does not have public Internet access, make sure the following packages have been installed (all can be retrieved from the yum repo epel, make sure to use the latest epel release repo):
Here’s the command to install these packages.
$ sudo yum install -y epel-release ntp
ulimit is used to limit and control the usage of system resources (threads, files, and network connections) on a per-process or per-user basis.
Run the following command to check the ulimit settings.
$ ulimit -a
The following settings are recommended when running YugaByte DB.
core file size (blocks, -c) unlimited data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 119934 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1048576 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 12000 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited
Setting system-wide ulimits
You can change values by substituting the -n option for any possible value in the output of ulimit -a. Issue a command in the following form to change a
$ ulimit -n <value>
-f (file size): unlimited -t (cpu time): unlimited -v (virtual memory): unlimited  -l (locked-in-memory size): unlimited -n (open files): 64000 -m (memory size): unlimited   -u (processes/threads): 64000
- After changing a ulimit setting, the YB-Master and YB-TServer processes must be restarted in order for the new settings to take effect. Check the
/proc/<process pid>file to see the current settings.
- Changes made using ulimit may revert following a system restart depending on the system configuration.